Conventionally known methods of measuring the elastic modulus of a linear elastic body include: a method of applying static strain to an elastic body and measuring the stress to compute the elastic modulus; and a method of applying forced oscillation to a linear elastic body and computing the elastic modulus from the resonance frequency. These measurement methods are described in, for example, IIC REVIEW/2010/4, No. 43 P30-34 (IHI Inspection & Instrumentation Co., Ltd.).
Conventionally known methods of measuring the viscoelasticity of a viscoelastic body include a method of applying forced oscillatory displacement to a viscoelastic body and measuring the resulting stress or applying forced oscillatory stress to a viscoelastic body and measuring the resulting displacement to measure the viscoelasticity (for example, see IIC REVIEW/2010/4. No. 43 P30-34 (IHI Inspection & Instrumentation Co., Ltd.)). A rheometer is an instrument for measuring the viscoelasticity of a viscoelastic body using such a method. Types of rheometers include a cone and plate rheometer and a coaxial double cylinder rheometer, depending on the oscillator shape.
These rheometers apply shear deformation to a viscoelastic body sandwiched between an oscillator and a stationary object and measure the shear stress to measure the viscoelasticity, or apply shear stress to the viscoelastic body and measure the shear deformation to measure the viscoelasticity such as relaxation time, dynamic elastic modulus, and loss elastic modulus.
In the case where the viscoelastic body has complex viscoelasticity unable to be represented by a simple mechanical model, it is assumed that the viscoelastic body includes a plurality of spring elements and a plurality of viscous elements, and has a plurality of relaxation times. In such a case, the frequency spectrum of each of the dynamic elastic modulus and the loss elastic modulus is formed by superimposing the waveforms deriving from the plurality of relaxation times.
Viscometers for measuring the viscosity of a measurement object such as a fluid, for example, have conventionally been classified roughly into (1) capillary, (2) falling sphere, (3) rotational, (4) chemical, and (5) oscillatory, depending on the basic principle.
Of these, the following oscillatory viscometers have been proposed: a viscometer that determines the viscosity of a measurement object from the drive current when a sensitive plate is caused to electromagnetically oscillate in the measurement object at a predetermined amplitude (for example, see IIC REVIEW/2010/4. No. 43 P30-34 (IHI Inspection & Instrumentation Co., Ltd.)); and a viscometer that forces an oscillator to oscillate, obtains a frequency response curve indicating the correspondence between the oscillation frequency and the oscillation amplitude of the oscillator, and determines the viscosity from its Q factor.
Known methods of measuring the elastic modulus of a measurement object include: a method of applying static strain to a measurement object and measuring the stress to compute the elastic modulus; and a method of applying forced oscillation to a measurement object and computing the elastic modulus from the resonance frequency. These measurement methods are described in, for example, Nihon Reoroji Gakkaishi (Journal of the Society of Rheology, Japan), Vol. 29, No. 1 (2001), pp. 21-25.